The 2014 Tikrit massacre stands out as one of the most horrific attacks from ISIS.

ISIS released video footage of last year's massacre in Tikrit, now claimed to be the worst attack initiated in Iraq. Images of the group's largest one-day massacre shows militant fighters shooting men who are face down to the Tigris River. The video was uploaded on the jihadist forum channels.

Highlights

MUNTINLUPA, PHILIPPINES (Catholic Online) - Most of the victims from ISIS' murder spree last year are Shiite military recruits in Tikrit. They plead for their lives, explaining they just recently joined the Iraqi army.

According to the report released by the Agence France-Presse, there were at most 1,700 people captured by the terrorist group at the military base in Speicher, located near Tikrit. The captured men were executed in different places, but most of them were at the city's former presidential palace complex.

Screenshots of the horrible massacre were posted by some who keep track of ISIS social media activities; the 22-minute video includes earlier and newly released footage of the "industrial-scale" massacre. It shows the victims falling from dump trucks into shallow mass graves, laying side by side then shot one by one.

"The killing went on into the night and the video shows an excavator being used to move piles of bodies," stated Agence France-Presse.

Other images show a young boy executing prisoners on the banks of the river leaving a trail of red water behind. The boy, holding a pistol, ignores pleas for mercy as prisoners are thrown in front of him to be shot.

"This is a message I address to the whole world and especially to the Rafidha dogs, I tell them we are coming," said the unidentified ISIS official seen in the video wearing a military uniform.

The term "Rafidha dogs" was an insult the Shiite Muslims. The video was released just four days after 24 men were sentenced to death by hanging in Baghdad because of the Speicher massacre.